This invention relates in general to a telephonic alphanumeric data entry system, and more particularly, to a method of entering alphanumeric information into a cellular telephone.
Text input using the standard telephone touch tone key pad is typically slow and relatively difficult. The growth in text input required for generating email, instant messages, SMS and the like begs for a more productive text entry method. The standard telephone key pad is designed with only ten to twelve distinct keys, necessitating the interposition of some manner of translating device between the standard telephone set and the user""s needs in order to input alphanumeric data. A typical telephone keypad includes 12 push-buttons, or keys, disposed in a matrix of 4 horizontal rows by 3 vertical columns. Each of the keys has associated therewith a unique number 0-9 and the * and # symbols. Overlaid on each of these keys is typically one or more letters of the alphabet, distributed in groups of three to four letters per key. For example, the xe2x80x9c2xe2x80x9d key typically has the letters xe2x80x9ca-b-cxe2x80x9d imprinted thereon. In general, systems for translating touch tone signals into alphanumeric data are known. For example, U.S. Pat. No. 3,381,275 describes a translator system utilizing what is known as a xe2x80x9ctwin depressionxe2x80x9d translation technique. Additionally, U.S. Pat. No. 4,427,848 entitled xe2x80x9cTelephonic Alphanumeric Data Transmission Systemxe2x80x9d describes a method whereby the alphabetic characters are transmitted by depressing a designated key (e.g., *) a number of times equal to the relative position of the inscription of the character on the key (i.e., the placement division of the alphabetic character), followed by the depression of the key on which the character is inscribed. A return to the numeric mode may be effected by depression of a second designated key (e.g. #).
Another example of a numeric to alphabetic translator is described in U.S. Pat. No. 3,618,038 utilizing a xe2x80x9cdelayed depressionxe2x80x9d translation technique, wherein depression of keys having different durations are discriminated. For example, an alphabetic character is represented by first depressing a key indicative of the placement division of the alphabetic character (e.g. the 1 key for Division 1, the 2 key for Division 2, or the 3 key for Division 3) for a duration longer than a preset limit, e.g., 290 milliseconds. The key inscribed with the particular alphabetic character is thereafter depressed for a duration less than the preset limit. Return to the numeric mode is effected by depressing a fourth symbol (e.g. the 0 key) for a period greater than the preset limit.
Still another touch tone to alphanumeric translation technique has been proposed whereby an alphabetic mode is entered by depressing a first key (e.g., *), followed by depressing a designated key corresponding to the placement division of a particular alphabetic character (e.g., 1, 2, or 3), followed by depression of the key on which the alphabetic character is inscribed. In addition, other translation techniques whereby each alphanumeric symbol is represented by a specific sequence of DTMF signals, with each character separated by a specific designated DTMF signal (e.g. #) have been proposed. An example of such a translation technique is described in Broomfield et al, Electronics, xe2x80x9cMaking a Data Terminal Out of the Touch-Tone Telephone,xe2x80x9d McGraw Hill, Jul. 3, 1980.
Each of the above translation systems may have advantages in respect of the entry and transmission of certain types of data. However, such techniques are, in general, slow and cumbersome, in that different combinations of a plurality of keys must be depressed to transmit the alphabetic characters. Most people do not possess sufficient manual dexterity or patience to use such systems proficiently. In addition, a further problem is inherent in the prior art translation systems, in that the user is provided no feedback during the entry of the data. The user is provided no indication that any valid data character has been transmitted, much less an indication of the specific data character transmitted. Particularly in view of the multi-key entry techniques, mistakes in the data often occur.